PWB with temperature sensor matrix allowing thermal imaging of the PWB

Abstract

An apparatus includes a printed wiring board including multiple layers including inner and outer layers. At least one of the inner layers includes an integral temperature sensor matrix. The temperature sensor matrix includes multiple temperature sensors arrayed over at least part of area occupied by the at least one of the layers. A method includes measuring information corresponding to temperatures in the temperature sensor matrix, and outputting indications of the information. The information may be displayed, e.g., as a thermal image of the printed wiring board.

What is claimed is: 
     
       1. An apparatus, comprising:
 a printed wiring board comprising multiple layers including inner and outer layers, wherein at least one of the inner layers comprises an integral temperature sensor matrix, the temperature sensor matrix comprising multiple temperature sensors arrayed over at least part of an area occupied by the at least one of the inner layers. 
 
     
     
       2. The apparatus of  claim 1 , wherein the temperature sensor matrix is formed within the at least one of the inner layers. 
     
     
       3. The apparatus of  claim 1 , further comprising a computer system configured to display temperature data from the multiple temperature sensors of the temperature sensor matrix on a display as a thermal image of the printed wiring board. 
     
     
       4. The apparatus of  claim 1 , wherein each of one or more of the multiple temperature sensors comprises a sensor element having a resistive circuit shape. 
     
     
       5. The apparatus of  claim 4 , wherein the resistive circuit shape is one of serpentine, rectangles, and squares. 
     
     
       6. The apparatus of  claim 1 , further comprising temperature reading circuitry configured to read information corresponding to temperatures from the multiple temperature sensors, and further comprising control circuitry configured to control the temperature reading circuitry to read information corresponding to the temperatures from the multiple temperature sensors. 
     
     
       7. The apparatus of  claim 6 , wherein:
 the temperature reading circuitry comprises: 
 a first set of multiplexers coupled to inputs of the temperature sensors in the temperature sensor matrix and able to select each one of a plurality of sets of the temperature sensors in the temperature sensor matrix to apply current through each temperature sensor in the selected set; and 
 a set of reading amplifiers coupled to outputs of the temperature sensors and able to read outputs from the selected set of temperature sensors; and 
 the control circuitry is configured to cause the first set of multiplexers to apply current to each one of the plurality of sets of the temperature sensors in the temperature sensor matrix and is configured to cause the set of reading amplifiers to read the information corresponding to the temperatures from individual ones of the plurality of sets of the temperature sensors. 
 
     
     
       8. The apparatus of  claim 7 , wherein the temperature sensors in the temperature sensor matrix are formed into N columns and M rows, wherein the sets of the temperature sensors in the temperature sensor matrix and selected by the first set of multiplexers are individual ones of the M rows, and wherein the set of reading amplifiers are coupled to outputs of each of the N columns and read information from each of the N columns. 
     
     
       9. The apparatus of  claim 7 , wherein the temperature sensors in the temperature sensor matrix are formed into N columns and M rows, wherein the sets of the temperature sensors in the temperature sensor matrix and selected by the first set of multiplexers are individual ones of the N columns, and wherein the set of reading amplifiers are coupled to outputs of each of the M rows and read information from each of the M rows. 
     
     
       10. The apparatus of  claim 7 , wherein the first set of multiplexers coupled to inputs of the temperature sensors comprises a plurality of groups of multiplexers, each group of multiplexers comprising first and second multiplexers and having a corresponding amplifier to provide current through the first multiplexer, wherein a second of the two multiplexers for each group is configured to feed back output of the first multiplexer to the amplifier for comparison by the amplifier with a drive voltage. 
     
     
       11. The apparatus of  claim 7 , wherein the control circuitry comprises one or more memories having computer readable code, and one or more processors, wherein the one or more memories and the computer program code are configured, with the one or more processors, to cause the temperature reading circuitry to read information corresponding to the temperatures from the multiple temperature sensors, and to output the information to another computer for display as a thermal image of the printed wiring board. 
     
     
       12. The apparatus of  claim 11 , wherein the one or more memories and the computer program code are configured, with the one or more processors, to cause the information to be converted from digital voltage values into corresponding temperature values prior to outputting the information to the other computer. 
     
     
       13. The apparatus of  claim 7 , further comprising a plurality of analog to digital converters coupled to outputs of the reading amplifiers, the plurality of analog to digital converters configured to convert analog voltages from the outputs of the reading amplifiers to digital values of the analog voltages. 
     
     
       14. The apparatus of  claim 13 , wherein:
 the temperature reading circuitry further comprises a second set of multiplexers, the second set of multiplexers coupled to the outputs of the reading amplifiers and each of the second set of multiplexers able to select one of a plurality of sets of the outputs of the reading amplifiers and to forward the selected set of the outputs of the reading amplifiers to the plurality of analog to digital converters; and 
 the control circuitry is configured to control the second set of multiplexers to select one or more of the multiplexers in the second set of multiplexers to cause the selected multiplexers in the second set to have their outputs routed to the plurality of analog to digital converters. 
 
     
     
       15. The apparatus of  claim 13 , wherein the control circuitry is further configured to convert the digital values of the analog voltages into corresponding temperature values. 
     
     
       16. An apparatus, comprising:
 a printed wiring board comprising multiple layers including inner and outer layers, wherein a selected one or more of the inner layers comprises an integral temperature sensor matrix, the temperature sensor matrix comprising means for measuring temperature, the means for measuring temperature arrayed over at least part of an area occupied by the selected one or more of the inner layers. 
 
     
     
       17. A method, comprising:
 measuring information corresponding to temperatures in a temperature sensor matrix, the temperature sensor matrix formed in a selected one or more of inner layers of a printed wiring board comprising multiple layers including inner and outer layers, the temperature sensor matrix comprising multiple temperature sensors arrayed over at least part of an area occupied by the selected one or more of the inner layers; and 
 outputting indications of the information. 
 
     
     
       18. The method of  claim 17 , further comprising reading the information corresponding to temperatures from the multiple temperature sensors and wherein the reading further comprises:
 selecting each one of a plurality of sets of the temperature sensors in the at least one of the temperature sensor matrices to apply current through each temperature sensor in the selected set; 
 applying current to each one of the plurality of sets of the temperature sensors in the at least one of the temperature sensor matrices; 
 amplifying and reading outputs from the selected set of temperature sensors. 
 
     
     
       19. The method of  claim 18 , further comprising outputting the information to a computer for displaying as a thermal image of the printed wiring board. 
     
     
       20. The method of  claim 19 , further comprising displaying temperature data from the multiple temperature sensors of the temperature sensor matrix on a display as the thermal image of the printed wiring board.